For example, a conventional safety circuit for an elevator installation as disclosed in JP-A 2001-106446 includes plural series-connected switches that operate in response to detection of any abnormality. When at least one switch operates, a signal for controlling an elevator is generated.
However, in the case where the switch is kept closed for a long time and resultingly welded at a contact, there is a possibility that the switch cannot be opened at the contact even though an abnormal elevator operation is detected, resulting in delayed or failed output of a control signal for an abnormality.